CYCLING PERFORMANCE TIPS

Cranks, Crank Length, and Pedals

Crank Length

Decisions on appropriate crank length are often steeped in mystique and considered part of the "art" of coaching for the competitive cyclists. Knee pain, especially chondromalacia, is often an indicator that your crank length is incorrect for you.

I did stumble across a nice review on the subject of picking your crank length. Other issues that have might be considered (you can make up your own mind on these) are:

1. It has been recommended that competitive cyclists use shorter cranks than the normally recommended to reduce the dead spot at the top of the cycle, from 9 to 12 o'clock (viewed from the rider facing to the right) and to allow a shorter stroke through the strongest leg movement. This would avoid having the knee bed less than 90 deg.

2. There is data showing that the shorter the crank, the higher the cadence that is possible (ultimately up to the rider). Shorter crankarms allow for faster cadences and improve cornering clearance on velodromes and in criteriums. They also avoid the effect of long crank arms to close the hip angle and reduce power - a benefit for velodromes and time trials.

3. An increase in crank length leads to an increase in the lever arm and the ability to more force. Longer crankarms have long been touted as superior for hard steady efforts such as hill climbing and mountain biking. But studies have shown that while they change torque, power is unchanged and they require the rider to pedal a larger circle.

4. Competitive cyclists ride comparatively smaller gears on the track in sprinting events (as opposed to the road) to allow optimal cadence in the shortest time. This is especially the case on banked tracks where the sprinter needs to changed direction suddenly at times. This facilitates reaching optimal cadence in the shortest time ( accelerating out of the bends). The same effect occurs with shorter cranks. The use of longer cranks allows for more leverage and so more power but can lead to a dead spot at the top of the stroke for those with a less than perfect pedal action & strength . In endurance events where the requirement for high cadence is not as great, the extra leverage is of benefit.

If you change your crankarm length on your current set up, don't forget to adjust your seat height as changing crankarm length will change the distance from your seat to the lowest point of the crank cycle.

Here's a starting point for suggested crank lengths based on traditional wisdom - you can start here and then tailor them (up or down) to your own style and preferences:

• inseam < 29 inches - 165 mm crank
• inseam 29 - 32 inches - 170 mm crank
• inseam 32 - 34 inches - 172.5 mm crank
• inseam > 34 inches - 175 mm crank

And for those of you wanting to delve further into the subject, here is a link to a beta test version of a Crank Calc Program being developed by Nigel Jones of Machinehead Software.

To reinforce the above, here is a question posed to "Coach Fred" at www.raodbikerider.com entitled "Do Long Crankarms Help Time Trialing?"

Question: I'm a 36 and a competitive triathlete, usually placing top-5 in my age group. I use 170-mm crankarms but have heard that for time trialing, longer is better. Is that true? -- Harold F.

Coach Fred Matheny Replies: There have been studies of crankarm length, but the results aren't consistent. Some show that longer cranks provide greater leverage for turning big gears. Some show that shorter cranks foster greater speed via a faster cadence. And some show that crank length is completely individual. So, longer crankarms aren't a panacea for time trialing. In fact, there are dangers associated with them. The added length makes your knees bend more at the top of pedal strokes and extend more at the bottom -- both of which can lead to biomechanical injuries if you jump from 170 mm to, say, 180 mm. Also, longer cranks reduce cadence -- and a brisk cadence is the key to good time trialing. All this said, many time trialists use crankarms 2.5 mm longer than those on their normal road bike. Because 2.5 mm (one-tenth of an inch) isn't much, it rarely causes an injury. But the jury is still out on whether that bit of extra length actually improves performance.

PEDALS

Weight

I ran across this comment (paraphrased) on an online biking site. " I just spent $200 on nothing. My bike is pretty tricked out: titanium frame, carbon fork, Dura-Ace group, assorted gewgaws. The only exception is the pedals, clunky old Looks. Last week I'm riding with an ex-Cat 1 who says, you could drop a half-pound by getting some new pedals. After the ride I stop at my local bike shop and order some new, 277-gram Dura-Ace pedals. I've just dropped $200 to make 100 grams disappear from my bike. I guess it would be cheaper to shed a few hundred grams from my body."

Not true. Although this seems logical, some weight makes more of a performance difference than an equal amount elsewhere on the bike/body. And that is in the pedals, crankarms, rims and tires. It has to do with the fact that we are alwasy making small accelerations (and decelerations) as we ride - on the flats and on hills. Not big moves, but small changes in speed. With acceleration, inertia in the drive train and in the mass of the bike needs to be overcome - linear inertia in the total weight, and rotational inertia in the cranks and wheels. Rotational inertia is much more sensitive to a set amount of weight than the linear inertia to acceleration from an increase in your body weight or weight elsewhere on your bike. This is why a freind with new wheels will say - "I rode 70 miles and it felt like 50" - after getting a set of Ksyriums.

So remember, all weight on your bike is not the same. And if you are going to upgrade to decrease the weight of your bike, do the rims and pedals first.

Clipless Pedal Technique

Clipless pedals are generally easier to enter than the old toe-clip-and-strap type - if you take a few minutes to practice before your first ride on the road. You'll really like clipless once you learn the "twist out" style of release and it becomes a reflex. Then you'll be able to get out quickly and cleanly, even in emergencies.You shouldn't have to look down while engaging the pedals. That's time-consuming and potentially dangerous. The remedy? Practice a little before you get into that emergency situation. Here are a couple of ideas:

• If you are extremely nervous, you might consider lightening the release tension. Your feet should be able to twist out easily but not suffer unintentional releases.
• Do a little mental imagery to get ready. Think twist, not lift. The release motion should be in a flat plane. Keep your heel level - pivoting it away from your bike.
• Practice in an empty parking lot or other traffic-free area. Clip in just as you would at the start of a ride, from a standing start straddling the bike.
  • Let's say that you normally begin with your right foot on the pedal.
  • Push off and clip in the left foot while looking at the pedal. The left crankarm should be straight up. Watch as you clip in and out several times. Fix in your mind the pedal's location and how your foot moves to engage it.
  • The next time, push off and clip in without looking. If you miss, look down, clip in once, then unclip and immediately try again with your eyes up the road.
  • Then, of course, clip in on the other side and you are ready to go.
  • Don't forget to clip out before you come to a stop - and at first do it on both sides. A common mistake for those just starting to use clipless pedals is to clip out on one side only and then fall to the opposite side - which makes for some exciting moments.
  • Repetition is the key. Do this several times on several separate days and you are ready for the road.
• Or practice on an indoor trainer. That way you can practice clipping out while the crank is any place in its 360-degree rotation.
• Take you first ride on a lightly traveled road. Look for a few stop signs to allow you to practice. Anticipate them, twist one foot out but keep it on the pedal about 10 seconds before coasting to a stop. This way you can put your foot on the ground to stop or, in the case of a light, snap back in and pedal away if it turns green.

This is the measurement between the pedal mounting surfaces (outside surface) on the crankarms (and indirectly the distance between the midline of each foot - which translates all the way up to the knees and hips.) The easiest way to determine Q-factor is to remove one crankarm and mount it in-line (not at the 180 degree rotation you use with riding) with the other, then measure the distance between the outside faces of the arms.

Another aspect is the distance between the crankarm and the pedal platform itself. You need more clearance there if your ankle bone hits the crankarm, if you purchase wider shoes or if your winter booties rub the crankarm. You may feel more comfortable with your feet in an outward position (though a few riders prefer the opposite.) The ability to fine-tune Q-factor means that you can make two bikes match, such as your mountain and road bikes. Mountain bikes typically have a significantly wider Q- factor.

Some pricey pedals allow you to adjust the location of the pedal platform and thus the perceived "Q factor", but there are much less costly ways to do so. If you need only a couple of millimeters additional clearance, get a spark-plug washer at an auto-parts store and simply slip it over the pedal axle before you thread it into the crankarm. Depending on the length of the threaded portion, you may be able to use two or three washers for greater spacing. Make sure there's at least half an inch of thread on the pedal shaft in the crankarm.

Is this a big deal for riders? Plenty of serious riders who train and race on road bikes and mountain bikes experience two different Q-factors without problems. So I'd adjust for what feels right for you.